Getting some personal gain I think it's kind of necessary to keep the system running. But I mean little momments of happiness, that's what I call gain, score a goal if you play soccer, write a good program if you are a programmer, write a wonderful piece of music if you are a composer, all these bring some little moments of happiness that need to exist in regular intervals to keep the system running as I said, which means that they are by no means the entirety of what is valuable. They are only the gasoline.
This kind of gain is needed. But..........
There is something odd. I've come to believe that if you seek it, you kill it. It's a butterfly-wings like phenomenon. You touch it, bang it's dead, it loses it's purity. Therefore I believe you should embrace personal little "gains" but not seek them because you MIGHT (depends on the character) start becoming some kind of hedonist which is PRACTICALLY bad (I hate preachers, if it wasn't genuinely bad I wouldn't preach about it just because I hated the word).
Personally I rarely think about my personal gain. And I found that even if I try. I can't. I like to build things, create little worlds inside the GREAT ONE (interpret that as you will but I mean music, automations, etc). It also fulfills me to interact with some people that are worthy. Living a life in accordance to something, which something after years and years of trying to define it you reach to the cocnlusion that it is the everything, so in accordance to the will of the cosmos and working to preserve the perennial values of beauty and purity.
To be honest as I'm sitting here right now I can't even think of an action I want to do, for personal gain. What the hell is personal gain anyway? Money? A piece of ass? You can get both of these if you live your life normaly and you don't opt being a bum.
Personal gain is far gone in the past for me, and I didn't even try. Being on a mission is my natural state.